One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You should be able to estimate when it's the best time to plant sunflowers by referring to the USDA zone info for Richardson.

Planting Calendar for Sunflowers

Frost tolerance for sunflowers:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Since sunflowers do not do well in cold weather it's necessary to wait until after the last frost has passed before you can plant them.

The earliest that you can plant sunflowers in Richardson is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant sunflowers and expect a good harvest is probably August. You probably don't want to wait any later than that or else your sunflowers may not have a chance to really do well. Starting your sunflowers indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost is on March 15 in Richardson. It might get as low as 10°F during the coldest months of winter.

Always keep in mind that USDA zone info for Richardson is just an average and the actual date of last frost changes from year to year. Since half of the time in Richardson last frost occurs after March 15 be ready to cover your sunflowers in the event of a surprise late frost.

USDA Zone Info for Richardson

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°F

This means that on a really cold year, the coldest it will get is 10°F. On most years you should be prepared to experience lows near 15°F.

Plants to Grow in Richardson

You may be interested in your other planting guides for Richardson.